1. Field of the Invention
Embodiments of the invention are in the field of robotics. More particularly, embodiments of the invention pertain to passive-type universal robot gripping and releasing apparatus and systems, associated methods, and applications thereof.
2. Related Art
Universal robot grippers are robotic end effectors that can grip a wide variety of arbitrarily-shaped objects. Proposed universal grippers have ranged from vacuum-based suction grippers to multi-fingered hands. These can be divided into two categories: active universal grippers and passive universal grippers.
Active universal grippers typically have an anthropomorphic, multi-fingered design, inspired by the human hand. Many such grippers have been developed, and multi-fingered grasping remains an active area of research. The active universal grippers that have been proposed are capable of both grasping and manipulation, but also engender extensive physical and computational complexity, which is evident in grasp algorithm research. The complexities of active universal grippers, coupled with their correspondingly high costs, have limited their adoption among commercial robotics industries.
Passive universal grippers, on the other hand, require minimal grasp planning. They are under actuated, and include components that passively conform to unique object geometries, giving them the ability to grip widely varying objects without readjustment (see, e.g., P. B. Scott, “The ‘Omnigripper’: a form of robot universal gripper,” Robotica vol. 3, pp. 153-158, September 1985; R. Tella, J. Birk, and R. Kelley, “A contour-adapting vacuum gripper,” Robot Grippers, D. T. Pham and W. B. Heginbotham, Eds. New York, N.Y.: Springer-Verlag, 1986, pp. 86-100; S. Hirose, “Connected differential mechanism and its applications,” Robot Grippers, D. T. Pham and W. B. Heginbotham, Eds. New York, N.Y.: Springer-Verlag, 1986, pp. 141-153; A. M. Dollar and R. D. Howe, “A robust compliant grasper via shape deposition manufacturing,” IEEE/ASME Trans. Mechatron. vol. 11, pp. 154-161, April 2006). For example Scott, id., reported a gripper design in which many independent telescoping pins could each passively slide in or out to conform to the shape of a target object, then pinch from the side to grip the object.
Passive universal grippers are generally simpler to use and require minimal visual preprocessing of their environment, but they too have had limited success gaining widespread adoption. Often their many passive components are easy to damage and difficult to replace. Passive universal grippers can be very expensive as well, and their ability to grip many different objects often renders them inferior at gripping any one object in particular.
One approach to achieving a lower threshold of universal gripping is to add deformable materials to the gripping faces of a traditional jawed gripper in order to increase the compliance of the surfaces. This technique is straightforward and can be sufficient for some applications. Simpson (D. C. Simpson, “Gripping surfaces for artificial hands” Hand, Vol 3, pp. 12-14, February 1971) was likely the first to suggest adding pockets of granular materials to gripping surfaces for this purpose, and later Schmidt (I. Schmidt, “Flexible moulding jaws for grippers,” Ind. Robot, vol. 5, pp. 24-26, March 1978) and Perovskii (A. P. Perovskii, “Universal grippers for industrial robots,” Rus. Eng. J., vol 60, pp. 9-11, August 1980) proposed designs that allowed vacuum hardening of similar grain-filled pockets to produce a custom gripper jaw shape. Reinmueller and Weissmantel (T. Reinmuller and H. Weissmantel, “A shape adaptive gripper finger for robots,” Proc. Int. Symp. on Ind. Robots, April 1988, pp. 241-250), while presenting a similar idea, went so far as to speculate that a single membrane filled with granular material might be able to grip an object on its own and function as a passive universal gripper. However, this idea was not demonstrated in practice or rigorously explored until the universal jamming gripper recently presented by us in E. Brown, N. Rodenberg, J. Amend, A. Mozeika, E. Steltz, M. Zakin, H. Lipson, H. Jaeger, “Universal robotic gripper based on the jamming of granular material,” Proc. Natl. Acad. Sci., vol. 107, pp. 18809-18814, November 2010.
Passive, universal jamming grippers exploit the temperature independent fluid-like to solid-like pseudo-phase transition of granular materials known as jamming (see, e.g., T. S. Majmudar, M. Sperl, S. Luding, R. P. Behringer, “Jamming transition in granular systems,” Phys. Rev. Lett., vol. 98, 058001, February 2007; A. J. Liu and S. R. Nagel, “Jamming is not just cool any more,” Nature vol. 396, pp. 2122, November 1998; M. E. Cates, J. P. Wittmer, J. P. Bouchaud, and P. Claudin, “Jamming, force chains, and fragile matter,” Phys. Rev. Lett., vol. 81, pp. 18411844, August 1998; A. J. Liu and S. R. Nagel, Jamming and rheology: constrained dynamics on microscopic and macroscopic scales, Taylor & Francis, London, 2001; C. S. O'Hern, L. E. Silbert, A. J. Liu, and S. R. Nagel, “Jamming at zero temperature and zero applied stress: the epitome of disorder,” Phys. Rev. E, vol. 68, 011306, July 2003; E. I. Corwin, H. M. Jaeger, and S. R. Nagel “Structural signature of jamming in granular media,” Nature, vol. 435, pp. 10751078, April 2005). This type of gripper leverages three possible gripping modes for operation: (a) static friction from surface contact, (b) geometric constraints from capture of the object by interlocking, and (c) vacuum suction when an airtight seal is achieved on some portion of the object's surface. These three gripping modes are illustrated in FIG. 1. By achieving one or more of these modes, the jamming gripper can grip many different objects with widely varying shape, weight, and fragility, including objects that are traditionally challenging for other universal grippers. For example we have successfully been able to grip a coin, a tetrahedron, a hemisphere, a raw egg, a jack toy, and a foam earplug. The gripper functions entirely in open loop, without grasp planning, vision, or sensory feedback.
When the gripped object is to be released, the gripper is vented to return to atmospheric (neutral) pressure and the object is let go. The performance of universal jamming grippers are limited by the need to reset the gripper between gripping tasks. An imprecise kneading or massaging procedure is often necessary to return the gripper to a neutral state (i.e., manually resetting the gripper), or else its ability to grip subsequent objects rapidly degrades.
In view of the foregoing disadvantages, shortcomings, and problems known in the art, the inventors have recognized the benefits and advantages of, as well as the solutions provided by, an improved passive universal gripping apparatus, systems utilizing one or more passive universal gripping apparatus, associated methods, and applications and, particularly, such apparatus, systems, methods, and applications that enable and utilize better object release, object ejection, and faster reset time.